Abstract
AbstractIn this work, the viscoelastic properties of acrylic‐based copolymer blends with poly(methyl methacrylate) (PMMA) and polycarbonate were investigated in the molten and solid states. High molecular weight copolymers of methyl methacrylate with butyl acrylate (MMA‐co‐BA) having varying molecular weight and composition were used to enhance the rheological properties in shear and extension. Blends containing up to 15 wt% of copolymer were prepared at 200°C and 150 rpm by using a DSM micro‐compounder. The samples were characterized by size exclusion chromatography (SEC), dynamic mechanical analysis (DMA), and rheology. The rheological properties were determined by using small amplitude oscillatory measurements (SAOM) in shear and a Rheotens™ device for melt strength determination. For PMMA, the effects of high molecular weight PMMA copolymer on the matrix were related to the molecular weight, the tacticity of the copolymer, and the individual components. The rheological properties in shear showed enhanced storage and loss moduli at low frequency, while no change was observed at high frequency. In addition, extensional viscosity measurements made by using the filament stretching technique showed a significant increase in melt strength compared to that of the base PMMA with the blend containing the highest molecular weight copolymer showing the maximum force and a reduced drawdown ratio. For polycarbonate, its blends with acrylic copolymer were found to be immiscible. Similar enhancement in the moduli at low frequencies was observed, but a significant increase in the viscosity was obtained as well, resulting from the response of the two‐phase system. This change in the rheological properties was further increased at 15 wt% loading. Owing to the formation of a phase‐separated morphology, the melt strength was found to increase only slightly. J. VINYL. ADDIT. TECHNOL., 12:143–150, 2006. © 2006 Society of Plastics Engineers
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